feat(simulation): contraband detection + dialogue confidence gate (D-075) (#425, #524)

Contraband detection (Task #425, D-065):
- New module: simulation/contraband.rs — NPC scan checks carried items
  against the KnowledgeGraph confidence gate. NPCs with Authority access
  can initiate a scan; scan outcome depends on item CarriedBy + KG entry.
- Adds ContrabandScanResult event type and ContrabanEntry component.
- Wired into simulation/mod.rs module list.

Dialogue confidence gate (Task #524, D-075 — OQ-18 resolution):
- relationship_to_trust() gains confidence parameter (KnowledgeConfidence).
- Trust tier mapping: (Friendly, KnowsDetails+)→Secret, (Friendly|Known,
  KnowsOf+)→Real, otherwise Surface. Access tier (Layer 1) unchanged.
- Caller process_talk_interaction passes observer KG confidence_of target.
- Resolves OQ-18: confidence co-gates TrustTier, not AccessTier.

Supporting changes:
- decisions/content.md: add D-075 (16 decisions, dated 2026-02-19)
- knowledge/types.rs: expose KnowledgeConfidence comparison helpers
- knowledge/registry.rs: minor API polish
- bridge/types.rs: ContrabandScanResult wire type
- bridge/text_renderer.rs: render contraband scan status
- perception/observer: include carried item count in snapshot
- npc/mod.rs: NPC scan range constant, authority flag

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/src/bridge/text_renderer.rs

@@ -161,8 +161,18 @@ pub fn format_snapshot_text(snapshot: &ObserverSnapshot) -> String {
 
     // Blocked entities (debug, #514)
     if !snapshot.blocked_entities.is_empty() {
-        let ids: Vec<String> = snapshot.blocked_entities.iter().map(|id| id.to_string()).collect();
-        writeln!(out, "Blocked (LOS): {} [{}]", snapshot.blocked_entities.len(), ids.join(", ")).ok();
+        let ids: Vec<String> = snapshot
+            .blocked_entities
+            .iter()
+            .map(|id| id.to_string())
+            .collect();
+        writeln!(
+            out,
+            "Blocked (LOS): {} [{}]",
+            snapshot.blocked_entities.len(),
+            ids.join(", ")
+        )
+        .ok();
     }
 
     writeln!(out, "===").ok();
@@ -288,6 +298,7 @@ mod tests {
             pending_recognitions: vec![],
             dialogue_response: None,
             blocked_entities: vec![],
+            scan_events: vec![],
         }
     }
 
@@ -410,6 +421,7 @@ mod tests {
             pending_recognitions: vec![],
             dialogue_response: None,
             blocked_entities: vec![],
+            scan_events: vec![],
         };
         let text = format_snapshot_text(&snap);
         assert!(text.contains("Tick 0"));